/*

 * jdapimin.c

 *

 * Copyright (C) 1994-1995, Thomas G. Lane.

 * This file is part of the Independent JPEG Group's software.

 * For conditions of distribution and use, see the accompanying README file.

 *

 * This file contains application interface code for the decompression half

 * of the JPEG library.  These are the "minimum" API routines that may be

 * needed in either the normal full-decompression case or the

 * transcoding-only case.

 *

 * Most of the routines intended to be called directly by an application

 * are in this file or in jdapistd.c.  But also see jcomapi.c for routines

 * shared by compression and decompression, and jdtrans.c for the transcoding

 * case.

 */



#define JPEG_INTERNALS

#include "jinclude.h"

#include "jpeglib.h"





/*

 * Initialization of a JPEG decompression object.

 * The error manager must already be set up (in case memory manager fails).

 */



GLOBAL void

jpeg_create_decompress (j_decompress_ptr cinfo)

{

  int i;



  /* For debugging purposes, zero the whole master structure.

   * But error manager pointer is already there, so save and restore it.

   */

  {

    struct jpeg_error_mgr * err = cinfo->err;

    MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));

    cinfo->err = err;

  }

  cinfo->is_decompressor = TRUE;



  /* Initialize a memory manager instance for this object */

  jinit_memory_mgr((j_common_ptr) cinfo);



  /* Zero out pointers to permanent structures. */

  cinfo->progress = NULL;

  cinfo->src = NULL;



  for (i = 0; i < NUM_QUANT_TBLS; i++)

    cinfo->quant_tbl_ptrs[i] = NULL;



  for (i = 0; i < NUM_HUFF_TBLS; i++) {

    cinfo->dc_huff_tbl_ptrs[i] = NULL;

    cinfo->ac_huff_tbl_ptrs[i] = NULL;

  }



  /* Initialize marker processor so application can override methods

   * for COM, APPn markers before calling jpeg_read_header.

   */

  jinit_marker_reader(cinfo);



  /* And initialize the overall input controller. */

  jinit_input_controller(cinfo);



  /* OK, I'm ready */

  cinfo->global_state = DSTATE_START;

}





/*

 * Destruction of a JPEG decompression object

 */



GLOBAL void

jpeg_destroy_decompress (j_decompress_ptr cinfo)

{

  jpeg_destroy((j_common_ptr) cinfo); /* use common routine */

}





/*

 * Abort processing of a JPEG decompression operation,

 * but don't destroy the object itself.

 */



GLOBAL void

jpeg_abort_decompress (j_decompress_ptr cinfo)

{

  jpeg_abort((j_common_ptr) cinfo); /* use common routine */

}





/*

 * Install a special processing method for COM or APPn markers.

 */



GLOBAL void

jpeg_set_marker_processor (j_decompress_ptr cinfo, int marker_code,

			   jpeg_marker_parser_method routine)

{

  if (marker_code == JPEG_COM)

    cinfo->marker->process_COM = routine;

  else if (marker_code >= JPEG_APP0 && marker_code <= JPEG_APP0+15)

    cinfo->marker->process_APPn[marker_code-JPEG_APP0] = routine;

  else

    ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code);

}





/*

 * Set default decompression parameters.

 */



LOCAL void

default_decompress_parms (j_decompress_ptr cinfo)

{

  /* Guess the input colorspace, and set output colorspace accordingly. */

  /* (Wish JPEG committee had provided a real way to specify this...) */

  /* Note application may override our guesses. */

  switch (cinfo->num_components) {

  case 1:

    cinfo->jpeg_color_space = JCS_GRAYSCALE;

    cinfo->out_color_space = JCS_GRAYSCALE;

    break;

    

  case 3:

    if (cinfo->saw_JFIF_marker) {

      cinfo->jpeg_color_space = JCS_YCbCr; /* JFIF implies YCbCr */

    } else if (cinfo->saw_Adobe_marker) {

      switch (cinfo->Adobe_transform) {

      case 0:

	cinfo->jpeg_color_space = JCS_RGB;

	break;

      case 1:

	cinfo->jpeg_color_space = JCS_YCbCr;

	break;

      default:

	WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);

	cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */

	break;

      }

    } else {

      /* Saw no special markers, try to guess from the component IDs */

      int cid0 = cinfo->comp_info[0].component_id;

      int cid1 = cinfo->comp_info[1].component_id;

      int cid2 = cinfo->comp_info[2].component_id;



      if (cid0 == 1 && cid1 == 2 && cid2 == 3)

	cinfo->jpeg_color_space = JCS_YCbCr; /* assume JFIF w/out marker */

      else if (cid0 == 82 && cid1 == 71 && cid2 == 66)

	cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */

      else {

	TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);

	cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */

      }

    }

    /* Always guess RGB is proper output colorspace. */

    cinfo->out_color_space = JCS_RGB;

    break;

    

  case 4:

    if (cinfo->saw_Adobe_marker) {

      switch (cinfo->Adobe_transform) {

      case 0:

	cinfo->jpeg_color_space = JCS_CMYK;

	break;

      case 2:

	cinfo->jpeg_color_space = JCS_YCCK;

	break;

      default:

	WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);

	cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */

	break;

      }

    } else {

      /* No special markers, assume straight CMYK. */

      cinfo->jpeg_color_space = JCS_CMYK;

    }

    cinfo->out_color_space = JCS_CMYK;

    break;

    

  default:

    cinfo->jpeg_color_space = JCS_UNKNOWN;

    cinfo->out_color_space = JCS_UNKNOWN;

    break;

  }



  /* Set defaults for other decompression parameters. */

  cinfo->scale_num = 1;		/* 1:1 scaling */

  cinfo->scale_denom = 1;

  cinfo->output_gamma = 1.0;

  cinfo->buffered_image = FALSE;

  cinfo->raw_data_out = FALSE;

  cinfo->dct_method = JDCT_DEFAULT;

  cinfo->do_fancy_upsampling = TRUE;

  cinfo->do_block_smoothing = TRUE;

  cinfo->quantize_colors = FALSE;

  /* We set these in case application only sets quantize_colors. */

  cinfo->dither_mode = JDITHER_FS;

#ifdef QUANT_2PASS_SUPPORTED

  cinfo->two_pass_quantize = TRUE;

#else

  cinfo->two_pass_quantize = FALSE;

#endif

  cinfo->desired_number_of_colors = 256;

  cinfo->colormap = NULL;

  /* Initialize for no mode change in buffered-image mode. */

  cinfo->enable_1pass_quant = FALSE;

  cinfo->enable_external_quant = FALSE;

  cinfo->enable_2pass_quant = FALSE;

}





/*

 * Decompression startup: read start of JPEG datastream to see what's there.

 * Need only initialize JPEG object and supply a data source before calling.

 *

 * This routine will read as far as the first SOS marker (ie, actual start of

 * compressed data), and will save all tables and parameters in the JPEG

 * object.  It will also initialize the decompression parameters to default

 * values, and finally return JPEG_HEADER_OK.  On return, the application may

 * adjust the decompression parameters and then call jpeg_start_decompress.

 * (Or, if the application only wanted to determine the image parameters,

 * the data need not be decompressed.  In that case, call jpeg_abort or

 * jpeg_destroy to release any temporary space.)

 * If an abbreviated (tables only) datastream is presented, the routine will

 * return JPEG_HEADER_TABLES_ONLY upon reaching EOI.  The application may then

 * re-use the JPEG object to read the abbreviated image datastream(s).

 * It is unnecessary (but OK) to call jpeg_abort in this case.

 * The JPEG_SUSPENDED return code only occurs if the data source module

 * requests suspension of the decompressor.  In this case the application

 * should load more source data and then re-call jpeg_read_header to resume

 * processing.

 * If a non-suspending data source is used and require_image is TRUE, then the

 * return code need not be inspected since only JPEG_HEADER_OK is possible.

 *

 * This routine is now just a front end to jpeg_consume_input, with some

 * extra error checking.

 */



GLOBAL int

jpeg_read_header (j_decompress_ptr cinfo, boolean require_image)

{

  int retcode;



  if (cinfo->global_state != DSTATE_START &&

      cinfo->global_state != DSTATE_INHEADER)

    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);



  retcode = jpeg_consume_input(cinfo);



  switch (retcode) {

  case JPEG_REACHED_SOS:

    retcode = JPEG_HEADER_OK;

    break;

  case JPEG_REACHED_EOI:

    if (require_image)		/* Complain if application wanted an image */

      ERREXIT(cinfo, JERR_NO_IMAGE);

    /* Reset to start state; it would be safer to require the application to

     * call jpeg_abort, but we can't change it now for compatibility reasons.

     * A side effect is to free any temporary memory (there shouldn't be any).

     */

    jpeg_abort((j_common_ptr) cinfo); /* sets state = DSTATE_START */

    retcode = JPEG_HEADER_TABLES_ONLY;

    break;

  case JPEG_SUSPENDED:

    /* no work */

    break;

  }



  return retcode;

}





/*

 * Consume data in advance of what the decompressor requires.

 * This can be called at any time once the decompressor object has

 * been created and a data source has been set up.

 *

 * This routine is essentially a state machine that handles a couple

 * of critical state-transition actions, namely initial setup and

 * transition from header scanning to ready-for-start_decompress.

 * All the actual input is done via the input controller's consume_input

 * method.

 */



GLOBAL int

jpeg_consume_input (j_decompress_ptr cinfo)

{

  int retcode = JPEG_SUSPENDED;



  /* NB: every possible DSTATE value should be listed in this switch */

  switch (cinfo->global_state) {

  case DSTATE_START:

    /* Start-of-datastream actions: reset appropriate modules */

    (*cinfo->inputctl->reset_input_controller) (cinfo);

    /* Initialize application's data source module */

    (*cinfo->src->init_source) (cinfo);

    cinfo->global_state = DSTATE_INHEADER;

    /*FALLTHROUGH*/

  case DSTATE_INHEADER:

    retcode = (*cinfo->inputctl->consume_input) (cinfo);

    if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */

      /* Set up default parameters based on header data */

      default_decompress_parms(cinfo);

      /* Set global state: ready for start_decompress */

      cinfo->global_state = DSTATE_READY;

    }

    break;

  case DSTATE_READY:

    /* Can't advance past first SOS until start_decompress is called */

    retcode = JPEG_REACHED_SOS;

    break;

  case DSTATE_PRELOAD:

  case DSTATE_PRESCAN:

  case DSTATE_SCANNING:

  case DSTATE_RAW_OK:

  case DSTATE_BUFIMAGE:

  case DSTATE_BUFPOST:

  case DSTATE_STOPPING:

    retcode = (*cinfo->inputctl->consume_input) (cinfo);

    break;

  default:

    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  }

  return retcode;

}





/*

 * Have we finished reading the input file?

 */



GLOBAL boolean

jpeg_input_complete (j_decompress_ptr cinfo)

{

  /* Check for valid jpeg object */

  if (cinfo->global_state < DSTATE_START ||

      cinfo->global_state > DSTATE_STOPPING)

    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  return cinfo->inputctl->eoi_reached;

}





/*

 * Is there more than one scan?

 */



GLOBAL boolean

jpeg_has_multiple_scans (j_decompress_ptr cinfo)

{

  /* Only valid after jpeg_read_header completes */

  if (cinfo->global_state < DSTATE_READY ||

      cinfo->global_state > DSTATE_STOPPING)

    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  return cinfo->inputctl->has_multiple_scans;

}





/*

 * Finish JPEG decompression.

 *

 * This will normally just verify the file trailer and release temp storage.

 *

 * Returns FALSE if suspended.  The return value need be inspected only if

 * a suspending data source is used.

 */



GLOBAL boolean

jpeg_finish_decompress (j_decompress_ptr cinfo)

{

  if ((cinfo->global_state == DSTATE_SCANNING ||

       cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) {

    /* Terminate final pass of non-buffered mode */

    if (cinfo->output_scanline < cinfo->output_height)

      ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);

    (*cinfo->master->finish_output_pass) (cinfo);

    cinfo->global_state = DSTATE_STOPPING;

  } else if (cinfo->global_state == DSTATE_BUFIMAGE) {

    /* Finishing after a buffered-image operation */

    cinfo->global_state = DSTATE_STOPPING;

  } else if (cinfo->global_state != DSTATE_STOPPING) {

    /* STOPPING = repeat call after a suspension, anything else is error */

    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  }

  /* Read until EOI */

  while (! cinfo->inputctl->eoi_reached) {

    if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)

      return FALSE;		/* Suspend, come back later */

  }

  /* Do final cleanup */

  (*cinfo->src->term_source) (cinfo);

  /* We can use jpeg_abort to release memory and reset global_state */

  jpeg_abort((j_common_ptr) cinfo);

  return TRUE;

}

